1. Field of Invention
The present invention is related to microwave bandpass filters and more particularly to the realization of compact size conductor-loaded cavity filters for use in space, wireless applications and other applications where size and spurious performance of the bandpass filters are critical.
2. Description of the Prior Art
Microwave filters are key components of any communication systems. Such a system, be it wireless or satellite, requires filters to separate the signals received into channels for amplification and processing. The phenomenal growth in telecommunication industry in recent years has brought significant advances in filter technology as new communication systems emerged demanding equipment miniaturization while requiring more stringent filter characteristics. Over the past decade, the dielectric resonator technology has been the technology of choice for passive microwave filters for wireless and satellite applications.
FIG. 1 illustrates the traditional dual-mode conductor-loaded cavity resonator. The resonator 1 is mounted in a planar configuration inside a rectangular cavity 2. Table 1 provides the resonant frequency of the first three resonant modes.
TABLE 1Resonant frequency of prior art dual-mode conductor loaded cavityresonators Metal puck: (0.222″ × 2.4″ dia), Rectangular cavity:(1.9″ × 3.2″ × 3.2″) Cylindrical cavity: 1.9″ × 3.2″ dia.Resonant FrequencyResonant FrequencyModeRectangular CavityCylindrical CavityMode 11.889 GHz1.940 GHzMode 22.506 GHz2.733 GHzMode 33.434 GHz3.322 GHz